purine nucleoside phosphorylases similar to human PNP and Escherichia coli PNP-II (XapA)
Human PNP catalyzes the reversible phosphorolysis of the purine nucleosides and deoxynucleosides inosine, guanosine, deoxyinosine, and deoxyguanosine. Patients with PNP deficiency typically present with severe immunodeficiency, neurological dysfunction, and autoimmunity. Escherichia coli PNPII, product of the xapA/pndA gene, catalyzes the phosphorolysis of xanthosine, inosine and guanosine with equal efficiency and has been referred to as xanthosine phosphorylase and inosine-guanosine phosphorylase. E. coli PNPII is also capable of converting nicotinamide to nicotinamide riboside, and may be involved in the NAD+ salvage pathway. It is one of two purine nucleoside phosphorylases found in E. coli, which also contains PNPI, which displays a different substrate specificity and belongs to a different subgroup of the nucleoside phosphorylase-I (NP-I) family than PNPII. NP-I family members accept a range of purine nucleosides as well as the pyrimidine nucleoside uridine. The NP-1 family includes phosphorolytic nucleosidases, such as purine nucleoside phosphorylase (PNPs, EC. 2.4.2.1), uridine phosphorylase (UP, EC 2.4.2.3), and 5'-deoxy-5'-methylthioadenosine phosphorylase (MTAP, EC 2.4.2.28), and hydrolytic nucleosidases, such as AMP nucleosidase (AMN, EC 3.2.2.4), and 5'-methylthioadenosine/S-adenosylhomocysteine (MTA/SAH) nucleosidase (MTAN, EC 3.2.2.16). The NP-I family is distinct from nucleoside phosphorylase-II, which belongs to a different structural family.
Structure:3F8W: Schistosoma mansoni PNP homotrimer bound with purine nucleoside adenosine and sulphate ion, in each of three active sites; contacts at 4A - View structure with Cn3D
Structure:1G2O: Mycobacterium tuberculosis PNP homotrimer bound with immucillin-H and phosphate in each of the three active sites; contacts at 4A - View structure with Cn3D
Comment:the neighboring subunit contributes residue(s) to the protein-ligand interaction
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